User blog comment:GalaxiaWild/Why are angels called demons in Devil May Cry 4?/@comment-5070432-20120731175255

It might also be the fact that Japanese culte doesn't have the same way of seeing demons as we do in Occident.

The closest thing in Japanese culture from our demons are youkais. Though, youkais aren't especially evil beings. Most of them are, but not all of them. Even so, "youkai" just mean it's a being superior to humans because of its powers, doesn't mean it's a demon.

So, if DMC universe considers superior beings as demons, angels should be considered demons too, despite not being evil.

Of course, I don't deny Flia's argument that seems totally more legit to me, since it's more related to the game itself than culture or names. So, I may just be saying useless stuff, but that could help too somehow... Or not. Doesn't matter.